Inverter circuit



l967 P. LANDIS 3,334,290

NvERTER CIRCUIT Filed Apri1 1 1964 zNVEITOR IIJ ATTORNEY cirouitc0mprising an inductive vvinding Series connected to said ad, a Switchelement connecting said v/inding t0 `a D.(:. Supply, a iirst Ineans foreectively maintaining the impedance of Said vinding Substantiallyc0nSant at a low value When predetermined normal magnitude 10ad currentiS Howing in Said vvinding and increasing the ilnpedance Of Saidvvinding t0 a Signific-antly higher value vvhen load current of higherthan normal nagnitude is Ovving in Said Winding to 1iInit the currentpassing therethrough, and a Second Ineans c00perating vvith Said il1-ductive vvinding for passing a Signicant portion of I)eri- 0dicresetting current, deve10ped in Said inductive Wind ing and representinga discharge of enefgy Stored in Said Winding f0110wing the inverterC01T1Inutati0n periods, di- Tectly back t0 the Supply Side of theinductive Mnding, Said rSt Tneans comprising a SatuTabIe core element ininductive coupled Telationship With Said inductive winding, and n1eansc00perating vvith said c0le elen1ent t0 S aturate Said core element in adirection opposing the effects 0f10ad current during nornlal values 0fload current vvllile Permitting greater than normal values of loadcurrent t0 desaturate Said core elenent z. AT1 impr0ved inverter Circuitfol' Supplying high frequency p0wer to a highlyinductive10ad, Saidcircllit c01nprising, in c0mbination: two primary SKritching devices,each connected in series vvith a Ovver Ineans and an ind uctive A C loadvvinding for alternately apply ing curfent in reverse directions throughSaid 10ad Winding, a current limiting ballast nleans connected in sefiesWith each of Said Switching devices and Said load winding, Said ballastIneans C01T1prising a saturable Teactor device, Said ilnpr0ved cifcuitfurther comprising a Shunt circuit connected acr0ss Said ballast Ineans,Said Shunt cifcuit conlprising a rectier device connected in parallelVith Said saturable reactor device to discharge periodicany aSignificant p0rtion of the energy Stored in said react01 device afterc0mfnutation, directly back t0 the input Side Of Said reactor devicevithout10ading Said pti1Tlary Svvitch ing devices.

3, The impfoved invefter circuit of claim 2' in Which Said Shuntcirc]1it further con1prises a resistance elenlent connected in seriesvvith Said fectifier device 4. The improved inverter Circuit Of clainl 3in Which Said Saturable Teactor device COInprises a first inductiveyvinding connected in series With each of said Svvitching devices andSaid load Winding, a Saturable core elenlent in inductively coupledrelationship With said lirst inductive vvinding, and biasing meansopepatively ass0ciated With said core elen1ent and Said first inductiveWinding for creating a Saturated magnetic eld opp0sing the eectS ofinitia1 Current OW during predetermined normal values of 10ad curfent inSaid first inductive winding of Said Saturable reactor device 5. Theinvertef cifcuit of clain^1 4 in yvl1ich Said biasing n1eans Of saidSaturable reactor device compfises a Second vinding inductively c0[1pledvvith said lrSt inductive vvinding and Said Core element, Said Secondvvinding electrica11y Connected, through a ballaSt device, to aIlindependent D C' power Supply means of Suicient l0vver Tating, to causeSaid Saturati0n Of Said Saturable feact0T device dur ing predeterminedn0rmal values of load current while pernlitting desatu ation there0fduring higher than I10TInal values of load curfent.

The inverter circuit of clain1 5 in Which Said Prinary Syvitchingdevices and Said recier devices COInPrise solid State elen1ents.

7. The inverter cifcuit of claim 6 in Which Said ri 1Tlary Switchingdevices are silicon contr01led Tectifiers with independenly controlledcontrol circuits.

References Cid UNITED STATES PATENTS 2,8ll,688 10/19 7 Kittl 32149 3 l09976 ll/1963 Sichling 32l4 x 3 13 l,343 4/1964 Reinert 3Zl16 3,207 9729/l96 Love 3214 X 3 Zl7 239 ll/196j Lunney 3Z1Zj X 3 263.l4 7/l966vvalker 3214

2. AN IMPROVED INVERTER CIRCUIT FOR SUPPLYING HIGH FREQUENCY A.C. POWERTO A HIGHLY INDUCTIVE LOAD, SAID CIRCUIT COMPRISING, IN COMBINATION: TWOPRIMARY SWITCHING DEVICES, EACH CONNECTED IN SERIES WITH A D.C. POWERMEANS AND AN INDUCTIVE A.C. LOAD WINDING FOR ALTERNATELY APPLYINGCURRENT IN REVERSE DIRECTIONS THROUGH SAID LOAD WINDING, A CURRENTLIMITING BALLAST MEANS CONNECTED IN SERIES WITH EACH OF SAID SWITCHINGDEVICES AND SAID LOAD WINDING, SAID BALLAST MEANS COMPRISING A SATURABLEREACTOR DEVICE, SAID IMPROVED CIRCUIT FURTHER COMPRISING A SHUNT CIRCUITCONNECTED ACROSS SAID BALLAST MEANS, SAID SHUNT CIRCUIT COMPRISING ARECTIFIER DEVICE CONNECTED IN PARALLEL WITH SAID SATURABLE REACTORDEVICE TO DISCHARGE PERIODICALLY A SIGNIFICANT PORTION OF THE ENERGYSTORED IN SAID REACTOR